Microstructure,Mechanical Properties And Corrosion Properties Of Mg-Y-Nd-Gd Magnesium Alloys

Due to the advantage of light-weight and high specific strength and stiffness,good forming ability and easy to cycle,magnesium and its alloys,by definition the lightest structural materials,are widely used in the field of aerospace and transportation.Due to the high mechanical properties at room temperature and high temperature,the rare-earth magnesium alloys are attracted more attention.To investigate the feasibility of WE43 magnesium alloy as a biomedical material,the effects of Zr and Gd element on the microstructure,mechanical and corrosion properties of WE43 extruded magnesium alloy were studied.In this paper,the microstructure and properties during the ageing,extruded+solid solution and ageing of rapid solidification GW123 K alloy were investigated.The effect of preparation methods on its performance was studied.The microstructures of the alloy at different states were observed by metallographic microscope(OM)and scanning electron microscope(SEM);the mechanical properties were characterized by tensile and compressive test;the phase of the alloy are analysed by X-ray diffraction(XRD);the corrosion properties were showed by the immersion corrosion experiment and electrochemical test.The experimental results show that Zr has the ability to refine the microstructure of WE43 extrusion alloy.Further addition of Gd has no refinement effects.The addition of Zr can increase the ultimate tensile strength and yield strength to 22% and 15%,respectively,comparing with WE43 alloy.Further addition of Gd element increase the tensile strength and yield strength of WE43-2 alloy to 262 MPa and 250 MPa,the increment is as high as 27.8%and 24%.On the contrary,the addition of Zr and Gd decrease the elongation of WE43 apparently.The results of corrosion test indicate that the adding of Zr and Gd does not affect the corrosion property of the alloy.The ultimate tensile strength and yield strength under 250?of extrusion GW123 K alloy had no change significantly,comparing with the room temperature tensile.The ultimate tensile strength and yield strength under 300? decreased obviously,but the elongation is to47.5%,4.3 times higher than that at room temperature.After T4 treatment,the ultimate tensile strength and yield strength of GW123 K were reduced to 27.7%? 24.7%,elongation to 14.5%,comparing with extrusion.The ultimate tensile strength and yield strength of GW123 K were increased to 42.4%?43.0%,elongation to 57.1%,comparing with extrusion at T5 treatment.After ageing treatment(100 ?,150 ?),the ultimate tensile strength was no obvious change compared with as-cast of Rapid solidification GW123 K alloy.But it was significant improved during the ageing treatment at 200??250??300? compared with that of as-cast alloy.The tensile strength was highest at 200 ? ageing treatment.At the same ageing treatment temperature,the tensile strength of the alloy increases first and then decreases,and to highest at the ageing time of 4h.The second phase was precipitated at grain boundaries.Compared with that of as-cast,the grains size has a tendency to grow up.The ageing treatment of 200?and 4h had the large number of secondary phase and well distribution.